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Thursday, May 23 • 2:45pm - 3:00pm
DTA Presentation - Characterizing the impact of the Kariba Dam on the geomorphology of the Zambezi River using a GIS based model

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Dams cause significant geomorphological changes to river systems by attenuating floods and preventing the transport of sediment downstream. Satellite images from the European Space Agency were used to understand the effect of the Kariba dam on the sediment transport of one of the world’s largest rivers, the Zambezi river, by developing bathymetric maps of the river downstream from the Kariba Dam. A calibration curve was developed using depths recorded in the field using a sonar-based depth sounder. Translation of sand bars is apparent on the maps and allows us to estimate the rate at which sand is moving downstream. The volume and velocity of these moving sand bars was measured by developing a GIS based model characterizing the depth of the river. Using high resolution multispectral images captured from the Sentinel 2A satellite on July 19th and September 2nd, 2018, the images were converted into a raster layer of pixels whose values represented estimated depths of the river at any given location. Sand bars, visible from high resolution satellite images, are present in reaches downstream of the Kariba Dam and have appeared to be moving steadily over time. Sediment transport to this reach of the river is essentially cut off by the dam leaving the source of these sediments unknown. It is likely that the river bed elevation is dropping as the sand washes downstream and is not replaced. Sand bars located in a reach of the river where image resolution and quality was highest were manually digitized in GIS. The rate at which they move downstream was calculated by measuring the distance between the position of the sand bars over the two images taken 44 days apart.


Thursday May 23, 2019 2:45pm - 3:00pm AKDT
GTCC RM 315 Tacoma Convention Center, 1500 Commerce St, Tacoma, WA 98402